USB 3.0 devices detected as USB 2 in ESXi 6.0 and 5.5

In my latest post USB Devices as VMFS Datastore in vSphere ESXi 6.0 I had a problem with USB 3.0 devices that are detected as USB 2 in ESXi. I know that USB 3.0, also known as eXtensible Host Controller Interface (xHCI), is supported in ESXi 6.0 and ESXi 5.5 Build 2143827 or later. Unfortunately all of my devices are detected as USB 2.1, despite the USB 3 hub was visible. This problem applies to both, USB devices in path-through mode, and USB devices mounted from the command line with usbarbitrator disabled. The solution was quite simple and not related to an ESXi, but to a UEFI configuration.

Within the UEFI the xHCI mode is configurable with a default of "Smart Auto". According to the documentation, in "Smart Auto" mode the USB 3.0 port acts like a 2.0 port before OS USB 3.0 drivers are loaded. For whatever reason, this does not work properly with ESXi. After setting xHCI Mode to "Enabled", all devices are correctly identified as USB 3.0.

The problem described here applies only if you see a USB 3.0 root hub but devices are connected to the wrong hub. If you do not see the USB 3.0 hub you have to verify that the xhci module is enabled and loaded with:

OMG! I've been having this issue for weeks. Especially with Windows 10 OS's. I broke out the same commands as you, but always thought it was the xHCI 0.96 implementation in ESXi 5.5. I thought an upgrade to 6.0 xHCI 1.0 would fix this, but didn't want to upgrade VC to 6.0.

I will have to try this when I get home and report back. Never thought to check the BIOS. Great find if it works.

Great finding! Unfortunately it doesn't work for me. I'm running esxi6 on Asrock H77M-ITX, and the only option for xHCI I have is to disable Legacy support. After doing that esxi still maps usb3 devices to usb2 hub. I'm so unhappy, because I want to use usb3 to gigabit adapter that brings WAN connectivity to the vm. In the usb2 i don't get higher speeds than 6Mbps, which is unacceptable.
Bummer! :(

Do you have a hint for a NUC6 owner if the above mentioned BIOS setting for USB is _not there_? :-)
I tried BIOS version 42-54 - and the option is not there.
My ESXi runs from an usb stick and i have the issue described in the article. Any other hint in forcing it to use the xHCI Hub/controller?